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Hyper-V VSS Writer RRS feed

  • Question

  • If I select only 1 VM for backup through the Hyper-V VSS writer, will only that 1 VM really get quiesced or will all of the VMs on that volume also be quiesced?

    Also, on restore, has anyone successfully used VSS to restore a VM? If the answer to the above question is that all VMs get quiesced on that volume, is it possible to use the Hyper-V VSS writer to restore a single VM on a given volume?

    I hope this is possible but I believe that the Hyper-V writer operates at no resolution finer than the volume level. I think that, even though I'm only selecting a single VM while enumerating through the components in the Hyper-V writer, it's still kicking off VSS in all the guests on that host volume. Thanks for any input.


    ~billy
    Tuesday, March 17, 2009 5:25 PM

Answers

  • Hyper-V VSS writer treats "VM" as a unit for backup / restore. You can select a VM for backup or restore and only that VM will be involved in backup or restore operation even though there are other VMs on the same volume.

    When you are restoring a single VM on a volume, which has a number of other VMs on it as well, Hyper-V VSS writer will turn off only the VM selected for restore. It is the responsibility of backup application to only restore files of that VM on the volume, keeping other VMs intact.

    HTH,
    Anagha
    • Proposed as answer by Anagha_12 Wednesday, March 18, 2009 11:41 PM
    • Marked as answer by Vincent Hu Monday, March 30, 2009 8:29 AM
    Wednesday, March 18, 2009 11:40 PM
  • Hi,
     
    What did you mean by "If I select only 1 VM for backup through the Hyper-V VSS writer"? Did you use any program like Windows Server Backup or DPM?
     
    What's the meaning of "will only that 1 VM really get quiesced or will all of the VMs on that volume also be quiesced?" What's the meaning of quiesced? I guess your are meaning the backup will involve or affect the other VMs. If you are using the applicaion like DPM, you can backup and restore the individual VM without involve any other VMs.
    • Marked as answer by Vincent Hu Monday, March 30, 2009 8:29 AM
    Thursday, March 26, 2009 4:16 AM

All replies

  • Hyper-V VSS writer treats "VM" as a unit for backup / restore. You can select a VM for backup or restore and only that VM will be involved in backup or restore operation even though there are other VMs on the same volume.

    When you are restoring a single VM on a volume, which has a number of other VMs on it as well, Hyper-V VSS writer will turn off only the VM selected for restore. It is the responsibility of backup application to only restore files of that VM on the volume, keeping other VMs intact.

    HTH,
    Anagha
    • Proposed as answer by Anagha_12 Wednesday, March 18, 2009 11:41 PM
    • Marked as answer by Vincent Hu Monday, March 30, 2009 8:29 AM
    Wednesday, March 18, 2009 11:40 PM
  • Are you sure about that? I think you're speaking about how a backup application works, but I'm wondering about interacting with the VSS writer directly.  I understand that the individual components in the Hyper-V VSS writer are "selectable," but does the writer honor the selected flag for a given volume? Thanks.
     


    ~billy
    Thursday, March 26, 2009 2:48 AM
  • Hi,
     
    What did you mean by "If I select only 1 VM for backup through the Hyper-V VSS writer"? Did you use any program like Windows Server Backup or DPM?
     
    What's the meaning of "will only that 1 VM really get quiesced or will all of the VMs on that volume also be quiesced?" What's the meaning of quiesced? I guess your are meaning the backup will involve or affect the other VMs. If you are using the applicaion like DPM, you can backup and restore the individual VM without involve any other VMs.
    • Marked as answer by Vincent Hu Monday, March 30, 2009 8:29 AM
    Thursday, March 26, 2009 4:16 AM